Also any idea how many kwh it takes to make a difference to hot water, we have a 300 L tank with 2 x 3 kwh immersions of which one is wired via the iboost, 0.83 kwh went to heating hot water yesterday (after fully charging batteries) which I’m guessing would have diddly squat impact on a tank that size?
Same set up here, 300l tank, 2 heaters. We use about 1/2 tank a day (2 showers, a bath and general handwashing). A daily input of 6 to 8kW is enough to serve our needs and not have the boiler fire up for hot water. The bottom half the tank maximises energy capture of sunny days, at least surplus from today does a bit of preheating for tomorrow. A maxed out tank will do 2 days even if tomorrow is dark heavy rainy day. I've seen the tank take over 20kWh from mostly cold state on a good summers day.
YMMV
@Surfer - that's pretty much what I was considering as there's not much in the way of alternatives.
The specific heat of water is 4184 Joules per kg per degree C. So a 300L tank is 300kg, to heat it by 1ºC requires 300x4184 = 1255200 Joules. A Joule is one Watt for 1 second, so 1kWh is 3600,000 Joules. Which means 1kWh will raise the temp of the tank by just under 2.9º, and 0.83kWh by about 2.4ºC.
THIS is why SI units should ALWAYS be used.
Also any idea how many kwh it takes to make a difference to hot water
My most helpful spreadsheet!
Hit a milestone last night - first 24 hours without taking anything from the grid (system went went in last December). Previously the best we'd managed was about 10pm...
Battery dropped to 20% before we started charging again and should achieve similar tonight.
[url= https://live.staticflickr.com/65535/52676920416_01e1b01048_z.jp g" target="_blank">https://live.staticflickr.com/65535/52676920416_01e1b01048_z.jp g"/> [/img][/url][url= https://flic.kr/p/2ofSZcN ]1st 24 Hours Battery[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
Another sunny day forecast for tomorrow.
We've done the last 3 days and that included charging the car for a few hours! Average gain for the last 3 days has been over 17.5kWh a day and we're still only generating a max of 3.6kW at any given point from a 5.4kWp array. It's like magic!
Any body have recommendations of companies who install around Worcester ?
It’s like magic!
Haha us to. Had a few sporadic days end of Jan when we lasted all day into the next charge period off a full charge during Eco7, then enough solar to get the battery at 100% by sunset. All depends on us using the oven or not or if we are out for tea or at the cinema during the evening. Still paying about £2 per day to fully charge the battery so it should be interesting during the longer days when we may not even have to do that and yesterday I fed back almost 5kW so I actually generated more than I used during that 24hr period which is a landmark for us. Being a net contributor at certain times of the year looks achievable.
I recommended the company I used on here a little while back and although they are based in the North West I was happy with the whole thing, including the price. I wont put the name on here but DM me if you want it. No idea if they will travel that far but worth asking, they can only say no.
Moving my question as suggested..
I’ve a lux 5k hybrid inverter.
it takes 8kw input but the output is 5kw. My panels are 6kw.
so on a sunny day producing 6kw what happens? Do I lose 1kw?
so on a sunny day producing 6kw what happens? Do I lose 1kw?
Yes. You can have the biggest array in the world (kinda) but you will only get the maximum the inverter is set to output *
That said, your panels will not be producing the maximum that often so you're better off (within reason) having more potential production than the inverter can output.
[Another person with an inverter that will output significantly more than the standard allowed!]
* unless a hybrid inverter can simultaneously send a max of 3kw to the grid and the rest to the battery ...... I'm not well educated on hybrid inverters.
I’ve a lux 5k hybrid inverter.
it takes 8kw input but the output is 5kw. My panels are 6kw.so on a sunny day producing 6kw what happens? Do I lose 1kw?
If you don't have a battery, or if the battery is full, yes; if you do have a battery though, even if the inverter is producing 5kw AC it could still put 3kw above that straight into a battery.
In the UK a 6kwp system will likely not get much above 5kw so it's probably a moot point, mind.
unless a hybrid inverter can simultaneously send a max of 3kw to the grid and the rest to the battery …… I’m not well educated on hybrid inverters.
Yes they can; we have a 5kw hybrid inverter on an 8kwp array but I've seen it accept 6.2kw, so I guess the battery was charging at full tilt and the rest was being used or exported...
Doesn’t the array usually run at full chat in summer?
Not sure I understand the point about the standard. If we run the kettle or hob and the fridge and a few pcs then the draw will easily be 5kw or more.
If I want to make the system work in a power outage will an isolator switch enable this or does it still depend on the inverter, I’ve no idea how I tell what mine will permit.
Doesn’t the array usually run at full chat in summer?
Not really, clouds, sun angle, losses within the system all conspire to lower production a bit. There will be times when all the stars align and you're maxed out, but it's unlikely to be [# of panels] x [advertised panel generation].
Not sure I understand the point about the standard.
It's more to do with what the grid infrastructure around you can handle coming in.
If I want to make the system work in a power outage will an isolator switch enable this or does it still depend on the inverter, I’ve no idea how I tell what mine will permit.
It's not that simple. Most inverters are grid tied - if they do not see a connection to the grid then they will not work. It's a safety thing.
Your system will have an isolator switch between the inverter and the consumer unit - switch it off (to simulate a power cut) and see what happens.
[Hint - the inverter is going to shut down!]
Quite excited. Getting ours installed in 10 days time by a company recommended on STW.
18x 405w panels (half east/half west) should give 7.2kw capacity or about 5250kw per annum on the model.
Also twin Lux Squirrel Pod invertors to give 7kw max draw (this is important to us) and 12.8kw of Greenlinx battery storage.
All links in dynamically to Octopus Agile for low cost charging from grid as needed.
Will report back after its up and running.
Nice!
I've been cursing my E/W array recently - they're good in the '6' summer months but fairly crap during the winter.
Hence why I want to add a further south facing 2-3kw ground mounted - that would be a great combo as the extended generation times of an E/W array is really good in the summer.
@chb that sounds pretty gold standard. I assume you need two inverters for just the reason I’ve noticed?
Apparently the lux hybrid inverter has seamless switching in 0.1s for UPS. No idea what that means in practice?
Hybrid inverters normally have an "EPS" Emergency Power Supply output that will stay active running on battery power in a power cut. Normally it's connected to the mains like everything else, but in a power cut it will, after some delay, be isolated from the mains and connected to the battery instead.
Installers often connect a socket to this; theoretically you can have house circuits moved to it permanently or using a changeover switch but it's a faff, expensive, there will be complications with earthing (you can't rely on the mains earth in a power cut) and probably not worth the effort. During a power cut you can still power things from this if the battery is not empty, and the inverter can still charge the battery from solar. It just won't export anything or run the normal house circuits.
The rating of the panels in "kwp" assumes perfect conditions such as sun shining square on the panel (which it won't be very often or at all) while the panel is cold (which it won't be if it's that sunny). I think the actual peak is normally about 80% or so of the nameplate rating.
any recommendations south of london? need to get some panels put on as part of an extension
Is the expense the change over switch and earthing?
Does the earthing need not apply to the standalone socket too?
Does the earthing need not apply to the standalone socket too?
Yes but it's considerably easier than a change over switch to implement correctly .
Mine is AC Coupled, so has three inverters. One for the panels and a dual/twin (think its two separate boxes but not sure) for the batteries. Each Lux Squirrel Pod can output 3.5kW so there are two of them (each with two 3.2kW Greenlinx batteries).
It does mean that to charge the batteries the you go from DC-AC- DC so marginal losses, but it means panels and batteries can run independently and top up from grid to batteries is automatically scheduled.
Hi, can someone please just put up link of 250-300L unvented water tank that can be used for future, if solar panels are added? So many tanks out there my mind goes blank!
I have to upgrade whole heating/hot water system, Currently combi but seems a tank would be better for future if we want solar. Also house will have 3 bathrooms fairly soon. Ta jon
I think you just need a cylinder with a direct means of heating (immersion) either as the only means or if you want to use the boiler as well then you need an indirect cylinder with an immersion which I think is almost all of them. Having two immersions one top and one bottom will enable a smaller amount of water to be heated, whether this is helpful or not depends how you use the 300l I think.
If you plan to have a thermo solar panel rather than one that generates electricity (pv) then you will need a twin coil cylinder.
Mains water pressure cylinders are referred to as unvented.
Thanks James, I think will be one that just allows 2 immersions? No need for thermal (I believe thats not really a thing now). Still would love a link as so confusing? Ta
the battery instructions for my solar batteries note that the voltage difference must be less than 100ma. Whilst this might be the case on day 1 presumably this might not be the case in the future..
So we’re up and running now.
I wondered though, is there any way to sense check whether everything is working as it should do and for example one of the panels isn’t duff? I’ve gone for optimisers so I’m guessing one or two having a problem won’t bring the whole lot down.
I have more questions..
my battery is apparently 47pct soc (so I assume around 2kwh as there are two batteries with 2.2kwh usable capacity each). But I am importing a few hundred watts from the grid. Why might this be?
But I am importing a few hundred watts from the grid
Unless you are exporting then all systems use a small amount of grid power but it should be around 40w per hour. A few hundred seems excessive.
I wondered though, is there any way to sense check whether everything is working as it should do
depends on your manufacturer and the software they provide. I have a Foxess system and the supplied software isnt particularly sophisticated so I installed Home assistant which provides very detailed data.
Hi, can someone please just put up link of 250-300L unvented water tank that can be used for future, if solar panels are added? So many tanks out there my mind goes blank!
I am upgrading my tank (vented) and I have an iBoost solar diverter which will support 2 immersion heaters. I also have a gas boiler which we use for heating water in the winter. 250-300L seems very large. I am looking about 150L.
Try these Gledhill
Is home assistant an app? Do you have a linky?
I’m not sure if the solar set up is using 400w I think it is just the gubbins in the house like fridge, pc, stuff on standby. It was more why hasn’t the battery dropped to something like 10 or 20 pct before calling on the grid. They are 90pct depth discharge I think so would have thought they would approach 10 pct?
depending on the invertor sometimes it will "balance out" a little and show it pulling from the grid. Also i have a luxpower and they say just use it as a guide. The data is meant to be viewed historically an sometimes when you looking at the instantaneous bit it can show some strange figures. 99% of the time though its right.
Andy. Do you have an app other than the lux one?
There is a minimum SOC that you can set within your battery config. I suspect you BMS will set that at around 10-20% to protect the battery and wont let you go lower than 10%.
I run Home Assistant on a Raspberry Pi and its easy to download HA and and set it up using an image. Have a root around here for the one thats right for you Home Assistant
I connected my inverter to my network using an Ethernet cable (bit of fiddling around on my Mesh network) and the Pi was able to connect directly. running the cable from my garage was the hard part. HA is a good bit of software and I am particularly keen on estimating my payback. HA allows me to do that very accurately. For example (with a bit of spreadsheet work) in February alone, so far, I estimate my electricity savings to be £105. With the lengthening days that is increasing day on day. So far very pleased with the outlay.
@5lab I'm not sure where you are south of London but we used Home Smart Energy based in Burgess Hill for a 3.6kWh 10 panel, inverter and battery installation last year.
Muddy@ out of interest how big is your battery and what sort of cost was that?
@muddy@rseguy thanks, we're just round the corner in Hassocks, I've been on a few muddyarse rides in my time as well (back in the day)
There is a minimum SOC that you can set within your battery config. I suspect you BMS will set that at around 10-20% to protect the battery and wont let you go lower than 10%.
Ours is set at 5% by default, but you don't actually know what that is 5% of as in what the minimum cut off voltage it, so it could still have plenty of margin or be very close to cells being exhausted...
Huawei system.
Nope.
I looked at HA and i just dont have the time / inclination atm
We have a Solar Edge system: PV, battery and water heater.
There isn't much you can configure, beyond the main preferences - eg water/ battery priority. All the technical tweaks or problem solving have to be done via Solar Edge helpline/ whatsapp chat. They are very helpful and responsive, but i'd rather be able to look under the hood a bit more i think.
Now the production has started to increase, and our road got an upgraded transformer that allows us to export, I'm starting to look around at different tariffs. Is anyone on Octopus Agile? The prices are starting to look pretty good now if you can load shift. There is also a new Beta tariff from them called Flux, that is designed for PV/battery owners without an EV Flux
Really hard to work out the relative merits, not least because our system has always been throttled by the export ban so i don't know how much the house is really capable of producing in the summer.
Oh. I've just seen in the small print that they only except 9kwP systems for Flux so that rules us out - although since we have an E/W split, there's no way we'd ever get to peak.
To benefit fully from the Flux tariff you need to discharge your batteries to the grid, my system doesnt support that. I use Eco7 which is still the best option for us at the moment.
HA is the game changer for me, without it (or something similar) then you are at the mercy of your installer and the limited data access that your vendor offers.
There isn’t much you can configure, beyond the main preferences – eg water/ battery priority. All the technical tweaks or problem solving have to be done via Solar Edge helpline/ whatsapp chat. They are very helpful and responsive, but i’d rather be able to look under the hood a bit more i think.
Same with Huawei, but you can just make yourself Admin and get 100% control e.g. I can tweak all the mains voltage control params and timeouts.
[url= https://live.staticflickr.com/65535/52702036742_eda8e508a0_c.jp g" target="_blank">https://live.staticflickr.com/65535/52702036742_eda8e508a0_c.jp g"/> [/img][/url][url= https://flic.kr/p/2oi6HpU ]Admin params[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
So on a cloudy February day what sort of proportion of output are you getting. Struggling to get 10 pct for me today 🙁
So many variables..... and it's a cloudy February day!
TBH as the owner of PV for about 9 or 10 years I'm well past getting excited about the output (well.... mostly) - but I get the "new adopter" interest in what's happening!
(but about 15% right now)
@sharkbait - thanks I’m interested partly as I’m trying to sense check if things are working properly in a new install. Albeit the chances of rectification are I expect nil unless it’s not working at all as any issue could easily be waved away because of one of the ‘ many variables’ as you say.
So on a cloudy February day what sort of proportion of output are you getting. Struggling to get 10 pct for me today 🙁
Why would you expect more? 10% is fine. you should be able to run the house on half of that and still store some power. Yield for the day would be 4-6kWh. We got 5.5 yesterday and even with two people working from home, cooking dinner, making HW bottles for bed, etc, we made it from 09:00>20:00 on just the solar.
Today, we've got clouds and sunny spells, so yield is already at 4kWh...You've got to view it on a monthly basis, not daily.
So far in Feb, we're at 210kWh of which we've managed to use 93%. With the extra battery which will go online this weekend, we'll increase that usage. Best day so far (in the life of my array - Dec 22 > now) was 18kWh.
TBH I think the only thing that could be wrong is a bad connection but I would have thought that would show up as either a massive, or zero, reduction in generation (depending upon single or micro inverters).
Either way I think these things show up better when there's a clear sky.
I had an 'issue' at our other place that I didn't find for 2 years!! I installed a diverter but nothing was being sent to the immersion even with everything switched off and the sun being out. Turns out the installers had fed the output from the inverter into the incoming (i.e. grid) side of our meter - so absolutely everything we generated went to the grid!!!
They didn't believe me when i told them and had to send pictures. Oh how I laughed when they had to send a an 'engineer' from Norfolk over to the far corner of N Wales to correct it - and pay me the compensation I was taking them to court for!!
(that's a bit of an edge case but without fitting the inverter I probably wouldn't have noticed that it was so incredibly wrong!!)
Stupid question alert. If I installed a 5kw array is that a max of 5kw over what time period (per hour, instant?) sorry nee to this and am thinking of heading down the solar route as my oil system is dying big style.
you should be able to run the house on half of that and still store some power. Yield for the day would be 4-6kWh. We got 5.5 yesterday and even with two people working from home, cooking dinner, making HW bottles for bed, etc, we made it from 09:00>20:00 on just the solar
I think your statement should be qualified with the size of your array and location - TBH I'm really struggling to see how you could possibly be generating power at 8pm when the sun set here at 5:30pm!!
Best day so far (in the life of my array – Dec 22 > now) was 18kWh.
Def NOT a 4kW array - my best so far is 6.5kW (but thats on a E/W array and it's too early in the year for it to come into it's own)
BTW it would be in a totally un obstructed perfectly south facing roof up a hill.
am thinking of heading down the solar route as my oil system is dying big style.
Which part of an oil system do you intend to replace with solar.
Heating hot water, central heating is already being looked at with a hook up to my existing back boiler on my wood stove.
It would have been quicker to kindly answer my question that question my methods though 😁
If I installed a 5kw array is that a max of 5kw over what time period (per hour, instant?)
It's the theoretical maximum the panels can instantaneously produce in lab conditions. The reality is that you will get a margin less than that as the stars rarely align perfectly* (panel production reduces somewhat as heat builds up).
Additionally, chances are the inverter will be limited to a maximum output of 4kW at any one time regardless of the input.
* In fact, almost never! Even when the it's a clear blue sky all day the angle of the sun to the panels in the morning and afternoon will lower the output. This is why the graph for a [south facing] perfect days generation looks like a hill with the peak being when the sun is highest in the sky - after the peak the generation will decline as the sun moves around and falls.
It's at this time when a E/W facing array is beneficial as it will start/stop generating earlier/later than a S facing array. Battery storage has negated some of that advantage but not all.
Thank you
I think your statement should be qualified with the size of your array and location – TBH I’m really struggling to see how you could possibly be generating power at 8pm when the sun set here at 5:30pm!!
Perhaps if you read more carefully you'd be less confused?
you should be able to run the house on half of that and still store some power
we made it from 09:00>20:00 on just the solar.
Perhaps it could be written clearer 😉
Could be read as you were making power between those times!
As written that's what it says sharkbait it's not just you.
Fwiw it's sun angle that's the killer.
It's pishwet and raining here today but the clouds are bright due to the sun behind behind them high in sky
We still generating 1kwH currently
Similar conditions in December would yield 200wh as sun has much more atmosphere and cloud to get through
Best day so far (in the life of my array – Dec 22 > now) was 18kWh.
And this is why people should qualify some statements with a description of their array, because this ^ could lead people, who are thinking about spending money on PV, to believe that they can fit a standard 4kWp system and generate more than enough power all year, when the reality is probably very different.
@daffy I’m way below that with 6kw array, split 50/50 se/sw facing. Managed a measly 1.4kw so far today.
Ours is a 5.5kWp array which is almost south facing (SSSW) at an inclination of 30deg. We're in the SW. cThe lower half of the array is in shade during the very first part of the morning at this time of year due to the neighbours house being slighty up the hill from us and having a higher pitch to their roof.
Since December we've generated just over 550kWh.
Looking at joining the solar party, it seems like a no brainer based on quotes so far, but let me know if I'm missing something.
One point to note is we're in a conservation area (Edinburgh) with about 50% flat roof which is partially shaded by cupola and chimney so those do limit system design somewhat so we'll max out at 3kwh tops I reckon.
Regardless of limitations if seems like a no brainer, £12k for a 3kwh system and battery, of which home energy Scotland will give £2500 grant and the remainder as a 12 year interest free loan.
Payback period on the system is only 8 years and savings over the lifetime are around £20k so seems like a no brainer, if you pay for it all as grant and loan then you only repay £70 a month on the loan and are saving more than that a month of the electricity bill. Even accounting for payback not as estimated for any reason, it's quite clearly a good cost saving as well as right thing environmentally.
Am I missing anything?
What's the size of the battery being offered?
One point to note is we’re in a conservation area (Edinburgh) with about 50% flat roof which is partially shaded by cupola and chimney
Planning? A flat roof would require a ground mount style frame to mount the panels - that's going to stand out somewhat! Is the shading going to encroach on a 3kW array or is 3kW the size that will be completely unshaded?
I have an unshaded S facing 3kWp system in N Wales and for 5 months of the year it produces less than £70 worth of electricity per month @ 35p/kWh.
(Annual production averages 3MWh)
Have you factored that in?
Recently had 4.8kWp Solar and 7.1kWh Storage. Lux hybrid inverter allows import and export settings. Paid £9.9K
On a dull feb day I am putting a couple of kWh in the battery at night on Octopus Go, so 15p, and the rest of the day is self sufficient. Generating 3.7kWh so far today has even topped up the battery
Very happy, I have only imported peak rate electricity 2 or 3 times in the last month
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What’s the size of the battery being offered?
10kw
Planning? A flat roof would require a ground mount style frame to mount the panels – that’s going to stand out somewhat!
Should be fine, tall narrow townhouses with a fairly narrow street means it's impossible to see any of the panels on the neighbours, ours would be the same. The guidance on what is acceptable or not is whether it's visible on the front elevation, which it isn't.
Is the shading going to encroach on a 3kW array or is 3kW the size that will be completely unshaded?
3kw is the unshaded section.
I have an unshaded S facing 3kWp system in N Wales and for 5 months of the year it produces less than £70 worth of electricity per month @ 35p/kWh.
(Annual production averages 3MWh)
Have you factored that in?
Awaiting the final proposal and drawings through but from what we went through yesterday, yes all of this is factored in. I've also got neighbours very similar system to compare against that should give me a good idea of real world generation versus theoretical.
I’ve also got neighbours very similar system to compare against that should give me a good idea of real world generation versus theoretical.
PVGIS shows an annual generation of about 2650kWh for your location (if you haven't looked already) and it tends to be really quite accurate.
Well Wales seems to be the solar power capital at the moment 😉 My 6.0 KW array was pushing almost 5.1 kw for quite some time earlier. It is a intermittewntly cloudy day here but am on 10 kWhs already generated. Yesterday was 16 KWh total. 218 LWh for February so far and 421 for the year. That is used and stored since I have no export capability. To be fair there has only been a few days of over generation and hence wasted output. A guess would be no more than 20 KWh lost
606kwh in aberdeen for the yr so far on a 5.3 array
@welshfarmer that's impressive. I would only get that percentage of the installed power on a sunny day in May - but my installation is 12 years old and I think the technology has improved significantly.
...... and the panels will perform better in the current low temperatures compared to warm summer temps.
Certainly wondering if my panel setup is fubar with those generation numbers. Possibly too much resistance on the cable run or other gremlin.
Having had a battery staying at high soc, noticed it’s at the other extreme now- 3 pct which feels too low!
EW split sucks in the winter unfortunately. It's only in the last week or so that our battery has been getting much charge. The worst days of january might only see 2 kWh. Last week the sun just seemed to suddenly get high enough for things to start working and we had a 22 kWh day. Will just about scrape 7 today and 300 for the month.
The summer is a different story as we can be generating from 0515 to 2115.
(Oxfordshire, 10kWp 35:65 E/W split, 50 degree angle on roof, 10 KWH battery)
Certainly wondering if my panel setup is fubar
Are you south facing or what? As @lodger said E/W is fairly crap in the winter but starting to get going now.
My set up is 3kw southwest and 3kw south east so not as bad as east and west. Was cloudy all day here with some rain and got approximately 2.5kwh for the day from 6kw panels.
PVGIS shows an annual generation of about 2650kWh for your location (if you haven’t looked already) and it tends to be really quite accurate.
Had not checked, thanks. This figure is almost on the nose of what our neighbours got last 12 months, and installer thinks he can squeeze a slightly bigger array onto our roof versus what they have (it's the same installer).
My set up is 3kw southwest and 3kw south east so not as bad as east and west. Was cloudy all day here with some rain and got approximately 2.5kwh for the day from 6kw panels.
Hmmm.
My 4kw E/W array produced 4.2kwh and it's been cloudy/rainy with a couple of bursts of short-lived sun.
Do you have micro-inverters or a single inverter, and if the latter is it dual mmpt?
You've probably just had more rain!
The s/w and s/e array are each meant to be on separate input to the inverter. each panel has got a tigo optimiser too.
